Todays modernized tanks, like the 100,000 pound, 800 horsepower U. S. M60, represent an awesome configuration of destructive power. However, this goliath can be easily disabled by the simple yet effective land mine. Various systems have been developed to detect and remove land mines, one of which is a plow type device mounted to the front of the tank and pushed through the soil to uproot and sweep aside an impending mine. These mine plows have been effective when utilized with powerful, heavy vehicles since the power and tractive effort are available to propel the plow through "tough" spots such as roots or clay or uneven terrain. These plows are also effective when plowing through relatively soft and consistent soils which require less power and tractive effort. However, when utilized on a light vehicle such as an assault amphibian vehicle (AAV), with limited tractive effort or when plowing through tough and inconsistent soils, prior art mine plows bog down and stop the plowing vehicle dead in its tracks. This is wholly inconsistent with battlefield tactics and can result in loss of both life and vehicle.
It was discovered that traction and horsepower were limiting factors and that plowing devices could operate satisfactorily on lighter, less powerful vehicles if the plowing depth could be maintained at a constant depth. The force required to propel a plow through the soil varies by the square of its depth in the soil. When a particularly "tough" spot was encountered, a plow would dig deeper into the soil placing a premium on tractive effort and power to overcome this "tough" spot. Bogging down was rarely a problem on the powerful, heavy M60 tank because the power and weight (i.e. tractive effort) were usually sufficient to maintain the desired depth of plow. However, when adapting the plow to lighter, less powerful vehicles such as the 50,000 pound, 400 horsepower AAV, the bogging down problem became acute at the required depth of plow (usually 8-12 inches). The reactive force from the plow would cause the front of the light plowing vehicle to raise up and thereby rotate the tips of the tines deeper into the soil effecting a deeper depth of cut.
Attempts have been made to overcome some of the deficiencies associated with prior art plows.
U.S. Pat. No. 4,491,053 to Bar Nefy et al discloses a mechanism for raising a mine plow while backing the vehicle and for preventing a deeper depth of cut while plowing.
U.S. Pat. No. 4,552,053 to Bar Nefy et al discloses a ground sensing means attached to the vehicle and a positioning means that function together to change the plowing depth from a location inside the vehicle.
U.S. Pat. No. 3,005,275 to Febre discloses a mechanical linkage system that automatically lifts the plowing blade of a tractor in response to forces acting on the plow blade.
U.S. Pat. No. 4,064,945 to Havey discloses an electronic control system which senses a plurality of transducers and produces a control signal to operate a control device.
U. S. Pat. No. 4,194,573 to Rettkowski discloses a pulled agricultural implements for breaking subsoil and a hydraulic system for raising the implements out of the soil for transportation on a highway.
However, none of these systems provide a simple, reliable, battle worthy mine plow that will operate on a light, traction limited vehicle to maintain a constant depth of plow when pushed by the front of the vehicle.